If someone is in dire danger, this commandment in the Torah insists that we must act. The ancient rabbis took this commandment so seriously that they teach us that even if it means breaking the Sabbath, even if it means breaking almost any other law, we must not stand by while someone is in danger of death. (The exceptions? We may not engage in murder, incest, or idolatry, even to save a life.)

Right now, in the United States, we are in the midst of a critical blood shortage. Last week, the American Red Cross reported that the nation’s blood banks were down by 50,000 pints. That is not a typo: FIFTY THOUSAND PINTS of blood — blood upon which people’s lives depend! — are simply not there. Each of those pints could make the difference between life and death for someone injured in the storms in the East, for a firefighter injured in Colorado, or for a mother with a complicated childbirth. Cancer patients sometimes need many pints of blood and blood products to continue fighting the disease.

Today I stopped by my local Red Cross Blood Donation center, and when the nurse looked at my record, she said, “Oh! Your blood type is negative! We really need those!” I asked her about the shortage and she shook her head: “Yes, it’s really, really bad. Now let’s get your blood pressure.”

Now I have a bandaid in the crook of my left elbow, and a sticker on my shirt. I don’t know where my pint of A negative will go, but I’m told it may save as many as three lives.

Some people can’t donate: my partner, a cancer survivor, is barred from ever performing this mitzvah ever again. A person with a fresh tattoo or piercing may not donate until 12 months have passed. A person who may have been exposed to any of several diseases may not donate. People who have taken certain drugs cannot. If you wonder if you are eligible, or you have other questions, you can find the answers on the Red Cross Blood Donation website. That site can also direct you to the nearest place to donate, and in many areas, you can make your appointment online.

The preservation of human life takes precedence over all the other commandments in Judaism. The Talmud emphasizes this principle by citing the verse from Leviticus [18:5]: “You shall therefore keep my statutes…which if a man do, he shall live by them.” The rabbis add: “That he shall live by them, and not that he shall die by them.” (Babylonian Talmud, Yoma 85b)

In Deuteronomy 30, Moses speaks to Israel with a message from the Divine, and near the end he says:

I call heaven and earth to witness you this day, that I have set before you life and death, the blessing and the curse; therefore choose life, that you may live, you and your descendants.

For those of us able to donate blood, we have a the opportunity to choose life in a very literal way. The choice before us is indeed a choice between life and death, blessing and curse.